In the treatment of many respiratory ailments it is desirable to treat the patient by means of aerosolized water or medicants which are inhaled directly into the lungs. In some cases the sought-for benefit can be obtained by enveloping the patient or, at least the trunk, head and shoulders of the patient in a sealed housing into which the medicant is introduced in aerosolized form, along with the necessary breathing air. Specific examples of such arrangements are croup tents, oxygen tents, incubators and the like. In other cases, it is essential that the medicants be introduced directly into the human or animal respiratory tract by connection of the patient to the nebulizer via surgical incision. An example of such circumstances is the treatment of patients recovering from extensive throat surgery in which a tracheotomy is required. In other cases, it suffices that a patient be treated by simply humidifying the atmosphere surrounding him or her as in many times accomplished in the home by room vaporizers and the like.
Regardless of how used or by what name identified, a successful medical nebulizer, vaporizer or atomizer should
a. be able to introduce a liquid preparation which may be water or some type of medicant into the carrier fluid to effect sufficient application of the medicant, PA1 b. be able to vaporize or atomize the medicant into an aerosol form which is comprised of a maximum of small high-respirable particles, PA1 c. be simple in operation, easily cleanned and sterilized and low in cost and maintenance.
As a result of these requirements and having in mind that, while an ideal nebulizer should meet each to the ultimate degree of refinement, the practical fact is that a home vaporizer need not be as refined as the equipment used in a hospital. Similarly, a nebulizer source to a crop tent would deliver a higher capacity of aerosol than a device used for post-operative treatment by direct respiratory tract application. Obviously, too, the cost of a home vaporizer differs radically from the cost of more sophisticated hospital equipment because hospital equipment should meet all of the stated requirements to the ultimate degree.
In view of such wide variations in application and requirements, there are on the market a wide variety of medical nebulizers of atomizers varying from the so-called steam vaporizers, available at any drug store, at a price of less than Twenty Dollars to the much more sophisticated and complex ultrasonic nebulizers sold to hospitals or individuals through medical supply houses and costing over Five Hundred Dollars. To date, there is not available one single piece of nebulizing equipment which can be sold at a reasonable price yet which will meet the wide variety of applications from simple home use to carefully regulated hospital techniques.
In recent times, a new technique has evolved for producing very fine spray of liquids. This technique involves the provision of dynamic film of liquid on a suitable surface and traversing the film with a stream of comparatively low pressure air whereby a portion of the film is atomized and carried from the surface in spray form. The fundamental concept is described and claimed in the U.S. Pat. Nos. 3,421,699 and 3,421,692, both dated Jan. 14, 1969 and issued to Robert S. Babington et al.
Preliminary studies of the technique proved the feasibility of producing a nebulizer capable of aerosolizing liquids to such a fine degree and in such dense form as to enable same to be inhaled directly into the respiratory tracts of human subjects. These studies further indicated that such a nebulizer was not only feasible but highly desirable because it would be simple in operation, relatively inexpensive, easy to maintain and above all, that by the application of various techniques and modifications of the basic apparatus such devices could be produced to meet the need for practically any type of inhalation therapy from simple croup tents to direct introduction of the aerosolized liquids into the respiratory tract.
The present invention deals with nebulizing devices and techniques to accomplish the desired results.
Accordingly, an object of the present invention is to provide a simple, easily used, inexpensive nebulizer capable of general medical use.
Another object of the invention is to produce a nebulizer which is capable of atomizing medicants to the ultimate degree of fineness to permit direct introduction of the medicant into the respiratory system of a patient.
An additional object of the invention is to produce a nebulizer which is virtually foolproof in operation and application.
Still another object of the invention is to produce a nebulizer which can be easily and simply cleaned.
A further object of the invention is to produce a nebulizer which is completely reliable and devoid of complex, expensive electronic or mechanical parts.
Still a further object of the invention is to produce a nebulizer which is so inexpensive as to permit the average patient to be able to afford proper respiratory therapy at home.
A further object of the invention is to produce a nebulizer which provides a maximum number of highly-respirable particles per volume of carrier air, so that with each breath a patient derives maximum benefit from the therapeutic aerosol.
These and an obvious myriad of other objects of the invention, not specifically set forth, but apparent to those skilled in the art, may be accomplished by utilizing the principles of atomizing liquids set forth in Babington et al. U.S. Pat. Nos. 3,421,692 and 3,421,699 in the form of a neublizer comprised of a base receptacle or flask; a spherical plenum having at least one aperture therein; air pressure means communicating with said plenum; feed means for depositing water or medicant in liquid form over said spherical plenum, said means may include an air lift pump for lifting liquid from the bottom of the base flask; a holding reservoir receiving the output of said pump, said holding reservoir having outlet means adjacent said plenum for depositing said medicant on said plenum surface. Heater means may be provided in the bottom of said chamber and means may be provided for automatically replenishing the medicant to the base receptacle. Additionally, the nebulizer may include spray impactor means for further reducing particle sizes of the aerosolized medicants or liquids and combinations of plenums and impactors may be provided to increase mass median density and capacity of a nebulizer to meet varying conditions and requirements.